I went onto this website to order some Crosby Anchor shackles for #40 RocnaAnchor and a Fortress FX 55 and have no idea which one is the best one to go for as there are over 20 different shackles and as the sizes are listed as 7/16 and the like (that measurement is about as useful to me as an ashtray on a motorbike - )

I personally like the ones with the bolt and split pin as it saves having to mouse the shackle. I just want to order the correct size as I am 10 000km from this supplier

Get a high test rated galvanized shackle with the biggest pin that will fit the chain. If you have 7/16 (11 mm) chain a 1/2" shackle with 5/8th pin should fit and be close to the same breaking strain as hi test G4 7/16 chain. (WLL 7200 lbs) - the recommended chain for a 40kg Rocna. Use calipers to measure the gap in the chain the pin will go through.

We use a Titan shackle but Crosby makes similar or maybe slightly higher WLL

I went onto this website to order some Crosby Anchor shackles for #40 Rocna Anchor and a Fortress FX 55 and have no idea which one is the best one to go for as there are over 20 different shackles and as the sizes are listed as 7/16 and the like (that measurement is about as useful to me as an ashtray on a motorbike - )

I personally like the ones with the bolt and split pin as it saves having to mouse the shackle. I just want to order the correct size as I am 10 000km from this supplier

Allways get the Crosby G-209A Shackle which is forged and MUCH stronger than any standard shackle.

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Bear in mind that the factor of safety used to calc the WLL is 4.5:1 for 209A shax as opposed to 6:1 for a standard 209 so MBS is not as great as it might seem - from memory WLL is twice, MBS is x 1.5.

We have run across the differences in safety factors before on CF. Mostly with chain grades but also with shackles. So to help with understanding we can do some math.

Crosby G-209 shackles are forged, quenched and tempered (presumed to be super carbon) with alloy pins. Their ultimate strength (us) is 6 times their working load limit (wll).

Crosby G-209A shackles are forged, quenched and tempered fully alloy steel shackles. Their untimate strength is 4.5 times their working load limit.

The numbers are in metric tons (2200 lbs) BTW.

Ah, did you see the mis-direction? Above you will note that the ultimate strength is X times the working load limit. But that is not really true.

The working load limit is actually 1/X of the ultimate strength.

In other words we do not go up to the US we go down to the working load limit. The reason G-209A has a factor of 4.5 and G-209 has a factor of 6 is that the steel of the G-209A is much stronger. Looking at it as US as a factor of WLL gives us an incorrect understanding.

Just looking at the numbers and we can see that in 3/8" the G-209A has twice the WLL and 50% greater US than the G-209. A total win here. Almost as good in the 7/16 too.

But the real "shocker" is when you compare the 7/16" G209 to the 3/8" G-209A. The G-209A is smaller but has a WLL that is 25% larger and a US that is the same.

You could go down one size in shackle size.... But of course I like shackles to NOT be the weak link in the anchor "chain" so I use the largest shackles that will fit (in G-209A).

Both the G-209 and the G-209A are proof tested to 2 X the WLL. The spec says that the shackle will not have any cracks or deformities that would prevent the pin from being removed after loading to the proof load. (The pin must be able to be removed by hand after the first turn.)

The point I wanted to make here is that both the G-209 and G-209A shackles will deform somewhere between the proof load and the US (ultimate strength). See the image.

The G-209 is more likely to deform closer to its WLL than the G-209A due to the "softer" steel. Some think that this is a feature.

Of course we do size shackles based in their WLL as the WLL is what is important to us.

The size of your chain is matched to your shackle. Sounds like you use 5/16" chain with a 40 lb anchor and an FX55.
A 3/8" pin will not fit through 5/16" chain.
Get a shackle rated above the strength of your chain but no larger than your chain. And ALWAYS seize the shackle pin with a bit of Monel wire or stainless wire.

In general you can fit a one side up shackle in any given chain. Thus for 5/16" chain you would use a 3/8" shackle.

The inside width of Acco 5/16" BBB and G43 chain is 0.500" where the pin diameter for a 3/8" Crosby G-209A shackle is 0.44". Plenty of room to fit.

In fact the Crosby G-209A 7/16" pin is listed at 0.5" and might just fit giving 2 sizes up.

In fact I do use a 7/16" Crosby G-209A shackle on my 5/16" G70 anchor chain. The pin just fits. In terms of normal variations in size I would guess that some links/pin combinations would fit and others not.

It is 10mm chain ..... I will measure that gap with an electronic vernier shortly and then get the correct shackle ..... I will also look at the Titan Shackles at
West Marine as I was not aware of that make.

This is the type of shackle style I would prefer as it is easier (IMHO) to mouse however it might snag given the comment above?

Bear in mind that the factor of safety used to calc the WLL is 4.5:1 for 209A shax as opposed to 6:1 for a standard 209 so MBS is not as great as it might seem - from memory WLL is twice, MBS is x 1.5.

Forget about the safety factor, whether it's 4.5 or 5 as we were taught as boilermakers.
Using it in any rigging situation is bad news. Whatever quality shackle you choose
(PROPERLY load tested) will offer an accurate WLL or SWL, (Safe Working Load; same thing) and that's the figure you rig with.
Moving beyond the WLL into the safety factor is a no-no.

The size of your chain is matched to your shackle. Sounds like you use 5/16" chain with a 40 lb anchor and an FX55.
A 3/8" pin will not fit through 5/16" chain.
Get a shackle rated above the strength of your chain but no larger than your chain. And ALWAYS seize the shackle pin with a bit of Monel wire or stainless wire.

I've had this exactly problem. Chain is 5/16. Bought a 5/16 shackle with a 3/8 pin and like you said, didn't fit. Well, I just used a file on the pin to fit the chain. How terrible is that?

I've had this exactly problem. Chain is 5/16. Bought a 5/16 shackle with a 3/8 pin and like you said, didn't fit. Well, I just used a file on the pin to fit the chain. How terrible is that?

How does that work?

Peerless (acco chain) says that their 5/16" chain has an inside of link width of 0.500" minimum for G43 and BBB. For 5/16 G30 it is 0.507" minimum. Even the boatmans pride G30 proof coil has a 0.490" width.

Crosby G-209A shackles in 3/8" have a pin diameter of 0.440" and the 7/16" has a pin diameter of 0.500"

So this says that a 3/8" shackle (with a 7/16" pin) will fit in most of the 5/16" chain. And that in some cases the 7/16" shackle (with a 1/2" pin) will fit in some of the 5/16" chain.

And in deed I am using a 7/16" Crosby shackle on my Acco G70 5/16" chain.

Oh, oh Oooo. I get it.

I'll bet that the shackle is not a "name brand" shackle and has a pin that is not in spec. That or the chain.

Peerless (acco chain) says that their 5/16" chain has an inside of link width of 0.500" minimum for G43 and BBB. For 5/16 G30 it is 0.507" minimum. Even the boatmans pride G30 proof coil has a 0.490" width.

Crosby G-209A shackles in 3/8" have a pin diameter of 0.440" and the 7/16" has a pin diameter of 0.500"

So this says that a 3/8" shackle (with a 7/16" pin) will fit in most of the 5/16" chain. And that in some cases the 7/16" shackle (with a 1/2" pin) will fit in some of the 5/16" chain.

And in deed I am using a 7/16" Crosby shackle on my Acco G70 5/16" chain.

Oh, oh Oooo. I get it.

I'll bet that the shackle is not a "name brand" shackle and has a pin that is not in spec. That or the chain.

How about measuring the chain width and the shackle pin diameter?

Regards.

My chain is DIN766. Internal diameter 9,6mm. The Titan shackle has a 10mm pin (not 3/8 as I mentioned, sorry).

I've had this exactly problem. Chain is 5/16. Bought a 5/16 shackle with a 3/8 pin and like you said, didn't fit. Well, I just used a file on the pin to fit the chain. How terrible is that?

Oh, no. I like to think you're kidding, but maybe not?
If you're out in the boonies and have to do the best you can with what you've got, I get it.
But otherwise I would not alter my rigging stuff. I've watched guys beat distorted shackles 'round' again with a 4 pound hammer so they can make the pin in the twisted thing. And then make a heavy lift with it! Shackles are a tool - and sometimes end up being the weak link when they are not treated as such.
If I see a shackle being abused on the jobsite, I'll do all I can to take it out of service. That means cutting it up with the torch, or throwing it in the drink.
A failure might be inconvenient - or it might prove disastrous.
Besides, if you're gonna reduce the size of your shackle pin, use a grinder. Saves a lot of time!